1. Field of the Invention
The invention relates to methods and devices for anastomosing a graft vessel to a target vessel, and more particularly methods and devices for forming such an anastomosis which is substantially suture-free or preserves native blood flow through the target vessel.
2. Description of Related Art
Despite the considerable advances that have been realized in cardiology and cardiovascular surgery, heart disease remains the leading cause of death throughout much of the world. Coronary artery disease, or arteriosclerosis, is the single leading cause of death in the United States today. As a result, those in the cardiovascular field continue to search for new and improved treatments.
Coronary artery disease is currently treated by interventional procedures such as percutaneous transluminal coronary angioplasty (PTCA), atherectomy and intracoronary stenting, as well as surgical procedures including coronary artery bypass grafting (CABG). The goal of these procedures is to reestablish or improve blood flow through occluded (or partially occluded) coronary arteries, which is accomplished, for example, by enlarging the blood flow lumen of the artery or by forming a bypass that allows blood to circumvent the occlusion. What procedure(s) is used typically depends on the severity and location of the blockages. When successful, these procedures restore blood flow to myocardial tissue that had not been sufficiently perfused due to the occlusion.
CABG, the most common surgical procedure to treat coronary artery disease, uses a graft vessel to deliver oxygenated blood to a coronary artery downstream of the obstruction in the artery. For example, in a typical CABG procedure a graft vessel, e.g., a section of saphenous vein, has one end attached to the aorta (proximal anastomosis) and another end attached to the coronary artery (distal anastomosis). The anastomoses are formed by suturing the graft vessel to the coronary artery and aorta, typically in an end-to-side manner. When properly formed, sutured anastomoses provide a blood-tight connection. Suturing therefore is the standard method for forming vascular anastomoses.
Although suturing produces a strong anastomosis when done correctly, the procedure is highly technical and time consuming due to the small size of the vessels being joined. The procedure is particularly difficult when carried out minimally invasively because of limited access to the heart and coronary arteries. Further, forming a hand-sewn anastomosis on a beating heart is very challenging for a majority of surgeons. Most CABG procedures are performed on a stopped heart despite recognized drawbacks associated with cardiopulmonary bypass.
Accordingly, there is a need in the art for methods and devices capable of forming vascular anastomoses quickly and easily on either a beating or stopped heart.
The invention provides methods and devices for forming anastomoses between vessels, e.g., a graft vessel and a target vessel. Pursuant to a first embodiment of the invention, a substantially suture-free anastomosis is created between the two vessels. Pursuant to a second embodiment of the invention, an anastomosis is created between a graft vessel and a target vessel so as to allow native flow through the target vessel to flow past the site of the anastomosis. The methods and devices of the invention may incorporate features of one or both of these embodiments.
According to the first embodiment of the invention, a preferred method for forming a substantially suture-free anastomosis between first and second vessels includes steps of providing a first vessel sized and configured for being joined to a second vessel having a lumen that is at least partially obstructed. At least a portion of the first vessel is placed adjacent the lumen of the second vessel so as to place the lumens of the first and second vessels in fluid communication downstream of the obstruction. The first vessel is fixed in position with respect to the lumen of the second vessel without using suture, thereby forming a substantially suture-free anastomosis between the first and second vessels.
Another preferred method carried out according to the first embodiment for forming a substantially suture-free anastomosis between a graft vessel and a coronary artery utilizes a stent-graft assembly including a stent movable between expanded and non-expanded orientations and a graft vessel attached to the stent, the graft vessel and stent being in fluid communication with each other. An opening is formed in the wall of the coronary artery and at least a portion of the stent in the non-expanded orientation is positioned in the lumen of the coronary artery. The stent is expanded into contact with the coronary artery to form a substantially suture-free anastomosis between the graft vessel and the artery.
A preferred device constructed according to the first embodiment is used to form a substantially suture-free anastomosis between first and second vessels and includes an expandable vessel coupling secured to a first vessel. The vessel coupling is in fluid communication with the first vessel and an expansion mechanism is provided for expanding the coupling. The vessel coupling is expanded to form a substantially suture-free anastomosis between the first and second vessels.
Another preferred device constructed according to the first embodiment is used to form a substantially suture-free anastomosis between a graft vessel and a target vessel and includes a stent-graft assembly comprising an expandable stent secured to a graft vessel with the lumen of the graft vessel in fluid communication with the stent. The graft vessel is adapted to be anastomosed to a coronary artery and the stent is sized and configured to fit at least partially within the lumen of the coronary artery when the stent is in the non-expanded orientation. An expansion mechanism is provided to expand the stent against the wall of the coronary artery to anastomose the stent-graft assembly to the coronary artery without suture.
According to the second embodiment of the invention, a preferred method for forming an anastomosis places a first vessel in communication with a second vessel while preserving native blood flow through the second vessel. The method includes steps of securing a first vessel to a second vessel without using suture to form a substantially suture-free anastomosis that is located distal to an obstruction in the second vessel, and allowing native blood flow in the target vessel to move past the site of the anastomosis.
A preferred device constructed according to the second embodiment is used to form an anastomosis between first and second vessels while preserving native blood flow through the second vessel. The device includes a first vessel secured to a vessel coupling in fluid communication therewith, the vessel coupling being configured to create an anastomosis between the first and second vessels while permitting native blood flow through the target vessel to move past the site of the anastomosis.
Another preferred device constructed according to the second embodiment is used to form a substantially suture-free anastomosis between a graft vessel and a target vessel while preserving native blood flow through the second vessel. The device includes a vessel coupling having first and second portions for forming an anastomosis between a graft vessel and a target vessel. The first portion of the vessel coupling is sized and configured to be coupled to a graft vessel so as to be in fluid communication with the graft vessel. The second portion of the vessel coupling is sized and configured to be coupled to a target vessel without using suture to form a substantially suture-free anastomosis that allows native blood flow through the target vessel to move past the site of the anastomosis.